Epoxy Over Oil Based Poly
If any polyurethane is to be used on your surface it must be oil-based polyurethane. Otherwise, the epoxy will not adhere correctly to the surface. Oil-based polyurethane is used over any surface with a coating on it that you do not know what it is or if it is incompatible with our epoxy.
It will form a layer between the non-stick surface and the epoxy allowing it to adhere to the surface without issues. The oil-based polyurethane does not replace the seal coat of the epoxy.